Backlight scanning technology divides a liquid crystal display into a plurality of areas based plane zones. In any area, the backlight (e.g., LED backlight) is turned on or off at suitable positions of the liquid crystal response curve. When the liquid crystal response curve is in a slowly ascending or descending phase (trailing phase), the backlight is turned off, so when the liquid crystal response curve is in a stationary phase, the backlight is turned on. The scanning backlight technology can improve the definition of a displayed picture, reduce the trailing phenomenon and increase contrast ratio. In order for the backlight source to keep the characteristics of being light and thin while being applied with the scanning backlight technology, an edge lighting type scanning backlight technology becomes a hot research topic.
Since liquid crystal pixel response is performed according to a row-by-row response manner, it is easier to apply the scanning backlight technology to a backlight source module having light bars at left and right sides of the display panel for horizontal control, and it may confront more difficulties to apply the technology to a backlight source module having light bars at upper and lower sides of the display panel for vertical control. But, the backlight source module having light bars at upper and lower sides has prominent advantages of heat dissipation over the backlight source module having light bars at left and right sides. Better heat dissipation can give rise to a longer life of service. Therefore, how to apply scanning backlight technology to the backlight source module having light bars at upper and lower sides has become an urgent issue to be addressed.